A photovoltaic cell module is generally constituted by a photovoltaic cell panel in which a photovoltaic cell element is formed, and a frame member referred to as a frame (a metal frame, etc.) surrounding the peripheral end part of the photovoltaic cell panel. The photovoltaic cell panel is covered by a protection member (for example, a cover glass and a protecting sheet using PET, etc.), to which the photovoltaic cell element, which is formed on a substrate, is adhered by a sealing material (for example, EVA and PVB, etc.).
Here, in a photovoltaic cell panel, from the viewpoint of safety, to prevent a user from receiving an electric shock by the electric power generated by the photovoltaic cell element, there is a need to provide a part, which is covered by an insulating member, along a certain distance (referred to as a creepage distance), between the photovoltaic cell element and the end part of the photovoltaic cell panel.
This creepage distance is described by referring to FIG. 1. Note that FIG. 1 is a cross-sectional view in which the end part of a substrate type thin-film photovoltaic cell panel is enlarged. In a photovoltaic cell panel 200 illustrated in FIG. 1, a photovoltaic cell element 220 is formed on a substrate 210, and a front surface protective layer 230 is adhered, by a sealing material 240, on the side of the substrate 210 on which the photovoltaic cell element 220 is formed.
The creepage distance is the distance from a portion that can be touched by a user (or the outer peripheral frame) to the photovoltaic cell element 220 (conductive part); the distance indicated by a dashed line L in FIG. 1 is the creepage distance. The creepage distance differs according to the requested specification; for example, the creepage distance is approximately several tens of mm.
Here, when the creepage distance is increased in order to increase the safety, the area of the photovoltaic cell element 220 with respect to the size of the photovoltaic cell panel 200 (power generation area) becomes small. As a result, the power generation efficiency per unit area decreases in the photovoltaic cell module (not illustrated) including the photovoltaic cell panel 200.
As a method of solving this problem, as illustrated in FIG. 2, the creepage distance can be secured by adhering an insulating material 600 (for example, an insulating tape, etc.) to the photovoltaic cell panel 200 so as to cover the light receiving surface, the end surface, and the back surface of the photovoltaic cell panel 200.
Specifically, referring to FIG. 2, by covering the end part of the photovoltaic cell panel 200 with the insulating material 600, on the light receiving surface side, the distance along which the insulating material 600 and the front surface protective layer 230 are adhering to each other is also considered to be the creepage distance (light receiving surface side), and on the back surface side, the distance along which the insulating material 600 and the substrate 210 are adhering to each other is also considered to be the creepage distance (back surface side).
As illustrated in FIG. 3, a frame 400 is attached to the photovoltaic cell panel 200 having the insulating material 600 adhered to the peripheral end part, to form the photovoltaic cell module. In the frame 400, a fitting groove 400x is formed by an upper flange 410, a back surface flange 420, and a side wall part 430. When attaching the photovoltaic cell panel 200 to the fitting groove 400x of the frame 400, in order to prevent the photovoltaic cell panel 200 from coming off the frame 400, there is a need to fill the fitting groove 400x with an adhesive material 700 such as a silicone resin and butyl rubber, etc., such that the frame 400 and the photovoltaic cell panel 200 are adhered to each other when attaching the photovoltaic cell panel 200 (see, for example, Patent Literature 1).
Alternatively, instead of filling the fitting groove 400x with the adhesive material 700 as illustrated in FIG. 3, an adhesive tape, etc., having an adhesive applied on both sides of the adhesive tape, may be used as the insulating material 600. In this case, the frame 400 and the photovoltaic cell panel 200 are adhered to each other via the insulating material 600 (see, for example, Patent Literature 2).